Adding a Drip Cap to Existing Windows

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Flashing windows, adding aluminum drip edge, by TwoPlusCute

I would like to make some naughty yet intelligent pun about flashing windows but nothing comes to mind. Here is the thing: it rained. Inside the house. Well, it dripped to be exact. And made a small pool on the inside of the window. The brand new window that well, was missing a little something: a drip edge cap above the window.

There was a drip cap above the window. However, it had to be over the trim (or brick molding) that is over the window. Semantics one might say…

We immediately called the Newbie House Owners’ Support Line (in other words, we called my father in law) and after a close inspection, he found out we lacked the all important drip edge cap above the new windows. Which we had to install as soon as possible because, the weather was about to change for the much wetter.

We had two days.

Two days may seem like plenty but, we also had to let the insulation dry as much as possible, before we water-tighten the area. A day and a half was all the time we had to let the water evaporate naturally, by opening the gap above the window on the exterior side. After that, we had half a day to fix the problem.


Water inside the windows, dripping from above
Uh, oh!


The other trick we applied, was sucking with a wet-dry vac from the inside, where the water had dripped. It might seem counter productive but, it did speed drying a lot. (It is practically impossible to do that from the outside because the windows are significantly above ground height.)

[If anyone wants a super detailed how to, I found this comprehensive guide on installing and flashing windows, that is pretty thorough.]

Running to a home improvement store (where I also bought 3 spray paint colors, only to regret all 3 of them the next day), we grabbed an aluminum drip edge (or drip-cap, or head-jamb flashing, this thing comes in all sorts of names) to the tune of $3 for 10 feet.

Ok, I thought, this isn’t as – financially – painful as I feared. Good news! Hubby didn’t seem to share my enthusiasm though, probably because he was envisioning himself, up the ladder, doing all most of the work.

And up the ladder he went. First, he had to remove parts of the siding above the windows and all the nails. Hubs was particularly annoyed with the nails.

Removing the siding to add a drip cap to our window flashing by TwoPlusCute
Removing the siding to install a drip cap


Which left us with this (yep, there is no water barrier there – a common practice in older days):


Exposed sheathing by TwoPlusCute


I cut the cap with a sheet metal cutter (it’s like powerful scissors), allowing a little extra length to overhang the edges of the window trim (and unlike this guy/guys, we measured before cutting).


With my favorite nose pliers I bent the edges in an angle, for the water to slope away from the siding and far enough from where the window meats the siding.


Snipping flashing drip edge cap by TwoPlusCute
Snipping and bending the flashing drip edge cap


It was not a precision job but it beats the flashing our old windows have. Which is none.

A hefty dose of mold resistant silicone (I am passionate about fighting mold) went exactly above the window trim (for the drip cap to sit on)


Caulking for the drip cap flashing, by TwoPlusCute
Adding a hefty dose of silicone caulking


and the edge cap was pushed firmly against it. (The black paper you see is window flashing.)


Pressing the edge drip cap firmly over the silicone, by TwoPlusCute
Pressing the edge drip cap firmly over the silicone, lifting the flashing tape behind it


After we secured the cap in place (with nails), all that was left was  replacing the siding and caulking every opening around the window with silicone. Because the old siding is rotten and chippy in most places, we put new boards in. (The rest of the siding will change too. One day. You know, once we budget for it.)

I helped with caulking (and managed to color coordinate my outfit with hubby’s). If I look awkward is because I am wearing hubby’s clothes that are a few sizes too big for me. Very stylish…


Adding window flashing, drip edge and closing the gaps with silicone by TwoPlusCute
Closing the gaps with silicone


I wasn’t thrilled about being on the ladder either but I was a tough cookie that day and finished caulking like a boss. See how I caulked the interior and all the tips you’ll ever need on using and choosing a caulking gun.

By now, the clock was ticking fast and the sun seemed set on…setting. We had to paint before nightfall not only so we could see what we were doing but also because the threat of rain was looming. The kind of siding we have – which is composite – is not really waterproof. Paint does all the job.

Well, there was no time for paint but there was time for a heavy coat of primer that provides a mold and mildew resistant film (that is a long way to say I used zinsser). I finished that just in time to take this exemplary nightshot (it exemplifies the need to use a tripod when shooting in half dark).


Finished adding drip edges over the windows, late at night by TwoPlusCute


Next day brought torrential rains (and some haze for good measure). No water seeped in so far and I do not think we will see any for a long, long time. This flashing is finally on the right spot.

Which is not above the window.

It’s above the trim that is above the window.


And next time we installed a brand new, new construction window, we remembered that. 😉



ps. We did finish the job by painting the new siding a couple days later, after the rains stopped and it was dry again.



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